Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1992-08-03
1994-02-01
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526254, 525276, C08F 1418
Patent
active
052833020
ABSTRACT:
Polyvinylidene fluoride (PVDF) having such crystallization properties as to produce small spheralite sizes without sacrificing properties, processability, purity, etc. comprises 99.5-96 wt. % of vinylidene fluoride and 0.5-4 wt. % of a comonomer selected from the group consisting of hexafluoropropylene, tetrafluoroethylene and mixtures thereof, has a logarithmic viscosity of 0.9-1.3 dl/g and a molecular weight distribution, as expressed by the ratio of weight average molecular weight to number average molecular weight, of 2.2-2.8. The PVDF is formed by suspension polymerizing vinylidene fluoride and 1-5 wt. % of the desired comonomer, in an aqueous medium in the presence of an oil-soluble initiator, so that a logarithmic viscosity [.eta..sub.1 ] of 1.3-1.9 dl/g is obtained at a vinylidene fluoride conversion of 10-50%; then adding a chain transfer agent to the medium and continuing polymerization so that the logarithmic viscosity [.eta..sub.2 ] of the final polymer is 0.3-0.7 dl/g lower than [.eta..sub.1 ] but remains in the range of 0.9-1.3 dl/g.
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Horie Katsuo
Suzuki Fujio
Wakamori Hideki
Kureha Chemical Industry Co. Ltd.
Sarofim N.
Schofer Joseph L.
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